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`H. A. FESSENDE-N.

SUBMARINE SI'GNALNG.

APPLICATION FILED MIMI. I3, 1918. v

1,3 1.1 1 57. j Patented July 29, 1919.

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CMIW# IVLLSSACHUSETTSY LSSIGNOR. TO SUBRHQ'E i' ,i fra z man @En l SIGNAL COMPANY, 0F PORTLE'D, MANE, Il. CEQPRA'IN DE MAENE.

Application filed March 13, 119113. Serial flo. 5122.659.

To @ZZ 'whom t may eminem:

Be it known lliat l, REGINALL" A. FESSEN- DEN, o'l' Brookline, in the county of Norfolk and Siate of lv'assaohuseti's, a citizen of the Unified States, have invented nei and useful l'mproremenlze in Submarine Signaling. of4

which the following is 'the specification.

My invention"relates to Signaling in ilnicl meclia and more especially to submarine signalin?. l

My invention has lor its object inoreasefl elic-iency in signaling; in fluid media and more especially in submarine signaling and Still more especially il; relates to a Secret system 0f submarine signa-ling whereby friendly submarines can communicate ,with each other and whereby they can send ouf secret recognition signals so thaty friendly submarino chasing vessels may recognize inem and not'l altempt to destroy 'them under the impreeion that they are enemy submarine veaaels, i

The invention is likewise' applicable to aeroplane Work, especially lo aeroplane 'Work at night time. l

The infrlosefl ligure, forming; a part of this; specilioation, allows, partly diagramniaically, suitable ineane` 'for carrying ont my invention. Here -11 is the Stern of a suhinarine; l2 lie propeller; 13 flie propeller' shaft; ll the motor driving the? propeller; 15. a remote olllitrol main circuit switch. which on heini! Closed starts the motor anll on being' opened cuis the current ol'from the motor. il? are lhe Storage bateries Jor driving the motor; i8 is a rotating make and break mecllanisni, having adjustable contacte l?? l?, 17 suitably spared about its periph erf/g il) is; a brush fr nmling eontao with die conaels l?, l?, i7 as the l-onlaet maker and 2041s a local battery foloperating the remote control ,main eirooit ee'il'oh l5. aiul 2l if a elegrapli key.

'The eperalion el the leviee is as Yolllmffs: `i The sillnnarinL-i i5 assnnnell lo lie traveling flnlnneitgeil. im rear'll'iing the area where ii flefsireil. fo onlie recognition olf alla lilo roa-infg' make anil break xmzfelianinn lil is in moiion so as to revolve at any Suitable Speed; for l-.ximiplm once per minute ami key 2l is ('losell. This being' (lone, over): time the @enfants 17, 17. l? (-onie in eonlar, with the brush l), the motor circuit is opened Specification of Letters raient. y Panam le@ lluiiy 29, Illg.,

for an for an pellen w The motor Will, of course, not stop ontirely as it will continue to revolve1 thongh `Tril/la rapidly 'climirlii'`lii11g, spcecl, owing to me lnertial'o'f the armature and Shaft, bnl,

applioant llas' found 'by actual trial that the cutting' off of the current from che mo'or even for an instant makes aV pronounced and marked change in the propeller noises and hull vibrations as heard through the *.valzere and consequently these brief interruptions of the motor circuit can be used for signaling lo a vessel equipped with apparatus "for iisteningto ille propeller sounds and hull vibrations through the Water.

The contaets i?, l?, 17,- heini;r adjustable,

may be varied from day to allay accord ance with a prearrangefl Schedule so tha 'on one day 'the recognition signal will lne a More@ il, on another clay a Morse l and on. enill another day a Morse il, ete.,

'and a trawler or destroyer which it ie clesired should recognize ille recognition signal. of the submarine ina-y loe furnished in all- Vance with the reeogniion signals` ior an entire monili if Thought desirable.

Should the submarine wish to telegraph to tran/1ers or (lesproyers or to another submarine, it may do i i by interrupting the motor circuit hy ille telegraph key 21 in' lhe same way as in ordinary laelegraphing".

'Tliismethod possesses a number of important atlvanageei l A. The reeogi'nmon sounds are produced hy varying' the rleeoi/ion Soumis ao that any I instant hy die remote control main 'i circuit SWltcn and iliemotor arma-ture ceaSeS- instant to exerta. torque on lyhe pro-` alight not, he heard aml the sulnnarine naigrlihl Sil leo

marine 'would not be heard in any case, beue ,if the unfriendly vessel does not hear the propeller sounds and hull vibra- QHS of the submarine it Will not hear the 5 recognition signal, and. vice versa.

C. he type of recognition signal is one which if bean-d4 .by an unfriendly vessel would naturally be supposed to be due to an accidental. stop age-of the motor, and the 10 signal is rupi y variable. l

In place of interrupting the motor current many other obvious devices may be used; for example, the clutch connecting the motor and the propeller shaft may be caused to 15 'slip 0r the making of lthe contacts may canse the motor speed t0 increase instead of to decreafse.

`dium which nsists in 'verviiw n fr n 'fluid medium, whereby inteiligm `What I claim ist-- 1. The method of slkrgnnling .1n u iin 1 in a predetermined manner lie u duced by the motion of a we mined signals may be givf'en. to n, f server.

2. The nieehod @if signe-ling; in :a dium which eoneists in. varying n m the spel/ed oft the propelling' m vessel traversing said iuid mediu ing to a predetermined code whe ligible signals may be given te e f server.

Bremen@ A. 

